There are a variety of manners in which voice data (e.g., a telephone conversation) can be transmitted. For example, the data can be sent as either an analog or digital signal over a network. The analog signal, known as Plain Old Telephone Service (“POTS”), is carried over the Public Switched Telephone Network (“PSTN”). The digital signals used to carry voice data include, among others, Voice over Digital Subscriber Line (“VoDSL”), Channelized Voice over Digital Subscriber Line (“CVoDSL”), Voice over Internet Protocol (“VoIP”), and Point-to-Point Protocol (“PPP”).
Regardless of the manner in which the voice data is transmitted, a voice data transmission channel can consume an unnecessarily large amount of network bandwidth in either an off-hook state or an on-hook state. An off-hook state is the state in which a transmission channel has been opened such that voice data can be sent from one party to at least one other party. An on-hook state is the state in which a first party cannot send voice data to another party without first opening a transmission channel to the other party or parties (e.g., moving to an off-hook state).
In an on-hook state, certain telephone service-related signals (e.g., a caller identification signal) must be sent over the network to a telephone even though no voice data is being sent. Some of these telephone service-related signals that are sent during the on-hook state are in-band signals (e.g., share the same transmission band as the voice data) while others are out-of-band signals (e.g., utilize a different transmission band than the voice data).
Out-of-band signals require networks that support different signaling bands for data traffic and voice traffic. In such a network, the out-of-band, on-hook signals are transmitted on the band for data traffic, and therefore, an open communications link for transmission of in-band signals during the on-hook state is not required.
However, a problem arises in networks that only have one communication fabric for both voice traffic and data traffic. For example, in-band, on-hook signals typically require an open communications link so that the signal can be sent without waiting for the communications link to be re-established. However, maintaining an open connection in this manner disadvantageously occupies network bandwidth even when no signals are being sent. This waste of bandwidth is undesirable, especially in a network that is capable of reallocating unused bandwidth among devices that are currently capable of transmitting voice or data traffic.